In the formation of thermoplastic fibers, the fibers are typically wound onto a forming package carried on the surface of a rotating mandrel or collet. The collet is rotated by a motorized winder which may be separate from or incorporated into the collet itself. In the case of glass fibers, filaments are attenuated through bushing tips in a bushing, coated with an aqueous binder and/or size, gathered into a unified strand, and wound onto the forming package. In addition to collecting the formed fiber strands, the forming package rotating on the collet supplies the attenuation forces necessary to draw the glass filaments from the bushing. The completed forming packages are then used in numerous industrial operations, for example, to form twisted textile yarn, tire cord, glass fiber roving and the like.
In operations such as the formation of tire cord and glass fiber roving it is often desirable to form a finished product having a length longer than that provided by the strands contained on a single forming package. To accomplish this, the ends of individual packages must be connected. Glass strand can be unwound from a forming package either from the outside or the inside. In either case, difficulties arise when a multiplicity of forming packages must be connected to one another.
When glass strand is unwound from the outside of a forming package, the strand is unwound until no strand remains. A problem with employing this method of unwinding is that the innermost strand typically has areas of excess coating and/or inconsistent diameter. The first problem is due to the tendency of the lubricant binder and/or size to migrate from the center of the package to the outer and inner layers during drying of the forming packages. Drying of forming packages is conventionally carried out in ovens to remove excess moisture present after the forming package is prepared. The second problem results from the variation in speed of the collet during start-up of the forming process. The same binder migration and inconsistent diameter problems on the outside of the package are often eliminated during end finding prior to using the forming package in a desired secondary operation such as twisting. Thus, prior to using a forming package, the package is end found by an operator so that it is certain that the strand entering a subsequent operation has all of its filaments. This procedure eliminates the outermost strand, which often has excess coating thereon caused by binder and/or size migration during drying and inconsistent diameter due to the slow-down and stopping action at the end of package formation.
Similar problems result when glass strand is unwound from a forming package from the inside. In this situation, the end finding process eliminates the excessively coated and inconsistent diameter strand from the inner portion of the package, however, now there is excessively coated and inconsistent diameter strand on the outer portion of the package. In addition to these problems, when strand is unwound from the inside, the only support that the forming package has is the outer strand. As the forming package nears its end there is less and less strand to support the remaining package. When support can no longer be maintained by the amount of strand remaining, the forming package collapses into a "bird's nest." Strand cannot be unwound from such a tangled situation and breakage of strand results. This results in a stoppage in what is desired to be a continuous process which, of course, adversely effects production.
In copending U.S. application Ser. No. 650,327 of David H. Griffiths, filed Jan. 19, 1976, now abandoned, and assigned to the assignee of the present invention, which is incorporated herein by reference, a forming package which is free of the problems typically encountered with forming packages, namely, a package which does not collapse when the strand is unwound from the inside of a package and which can be connected to a plurality of packages without the necessity of using excessively coated or inconsistent diameter strand is disclosed. The forming package includes a tie-on-tail which can be located either near the inside or near the outside end of the forming package. This tail provides a location for connecting a plurality of forming packages together without the necessity of connecting the very ends of the package to another package. When the tie-on-tail is located near the inside end of the package, such a package is used for unwinding strand from the outside. Thus, the tail eliminates the necessity of using inconsistent innermost strand of the package. When the tail is located near the outside of the package, the package is unwound from the inside. This eliminates the necessity of using the inconsistent outermost portion of the package and eliminates the collapse of the package and the resulting "bird's nest."
The apparatus employed includes an arm which has been timed to pull the strand out of the spiral over which it traverses at a desired time and to wind the tie-on-tail at an edge, preferably the inside edge, of the forming tube on which the forming package is wound at a desired time during the winding of the forming package. Such an operation requires an arm for removing the strand from the spiral, and apparatus connected to and timed with the winder to rotate the arm which pulls the strand out of the spiral.
It is desirable, therefore, to produce forming packages having a tie-on-tail thereon without the necessity of such additional apparatus.
In other glass fiber products, a tie-on-tail is not necessary, such as in forming packages of textile strand. These packages are transferred to a twist frame and twisted into yarn onto bobbins. Here, individual forming packages are employed without typing a plurality of packages together, as this process is not continuous.
In such applications, binder migration is also less of a problem, an entirely different type of binder and/or size being employed. The main problem of this type of package formation is the inconsistent strand which is wound at the very outer end of the package during slow-down and stoppage of the collet after a call down, the completion of a package.
It would be desirable, therefore, to isolate this inconsistent strand from the balance of the forming package.